Systems that locate, track, and monitor the status of people and valuable objects generally utilize or incorporate known technology, including, for example, Global positioning System (GPS) technology, inertial and non-inertial sensor devices, and signal analysis methods. However, existing systems have serious drawbacks that are based on battery power energy, antenna strength and effectiveness, available cellular services and satellite global position around earth.
For example, tracking GPS relies primarily on line-of-sight signal acquisition, for example, caves or certain terrain. In these locations, however, the line of sight of GPS satellites may be substantially obscured and GPS signals may be highly attenuated. As a result, GPS signals are typically weaker in these types of environments so GPS receivers have difficulty receiving GPS signals and calculating accurate position information.
Inertial tracking systems typically use readings from sensors such as gyroscopes and accelerometers to estimate the relative path of personnel and/or assets. Inertial systems, however, may accumulate large errors over time due to factors such as drift in sensor offsets, sensitivity, and measurement limitations of the sensors, as well as limitations of the location determining methods (e.g., algorithms) implemented by such systems.
Signal analysis methods that use signals of the same (or different) frequencies from different reference points to compute the location of personnel and/or assets may be unfeasible due to the need to install a number of reference devices at a particular tracking location (or scene), and may further have large instantaneous errors and outliers due to the multi-path effects of signals traveling through various building materials.
Due to these drawbacks, lost or stolen vehicles, personal valuables, and other objects often are not recovered quickly or successfully using existing tracking systems. Aircraft and watercraft may be lost and out of communication for extended periods of time. In addition, people in emergency situations may not be able to communicate their location to law enforcement authorities.
Therefore, there exists a need for a tracking system that provides a secure location signal from anywhere, even where there is no cellular network. There is also a need for a more powerful and effective miniature antenna structure for use with various wavelengths in smaller scales. Finally, there is a need for a communications system that can take advantage of global position and location information to provide real-time location identification and tracking for individuals, mobile devices, and other objects.